This invention relates to a pulley and shaft mechanism, more specifically, to a low-cost pulley construction incorporating a suitable mechanism for retaining and positioning the pulley on a motor shaft.
Electric motor shafts with pulleys attached thereto are well known in the art. For example, in home appliances, such as a washing machine, an electric motor is used to drive the agitator mechanism. To that end, the electric motor is designed having a shaft with a pulley secured to the exposed end of the shaft. The pulley engages a drive belt means for translating the rotation of the motor shaft to the agitator assembly.
Generally, pulley assemblies known to the art are complicated in construction and relatively expensive to manufacture because of that construction. For example, prior art pulleys with which I am familiar are stamped metal constructions. The pulley is formed from two metal stampings, which are then joined together mechanically in any desired way. Welding the parts often was the preferred assembly method. After assembling the pulley, it is mounted in its intended application. The motor shaft end that engages the pulley conventionally is threaded and the pulley is mounted on the shaft and retained on the shaft by a suitably threaded nut and washer assembly. The mounting portion of the shaft, including the threads, is generally at least partially of a lesser diameter than the body of the shaft. A washer or other retaining ring is placed over the threaded portion so as to seat against the shoulder formed where the threaded diameter meets the greater shaft diameter. The pulley seats against the washer or retaining ring to prevent retrograde moving of the pulley. Usually, another lock washer or retaining ring is slipped over the threaded diameter of the shaft and the nut is tightened thereon, securing the pulley in place. The threaded portion of the motor shaft is often formed in a special shape, that shape also being formed as an opening in the hub of the pulley, so that the shaft engages the pulley. This type of pulley and shaft assembly requires multiple parts: a washer or retaining ring, the pulley, which as indicated, commonly is assembled from two metal halves, another retaining ring or washer, and the threaded nut.
If there are variations in the shaft assembly tolerance motor to motor, washers or retaining rings of variable thicknesses or additional retaining rings that serve as spacers must be added to position the pulley appropriately on the shaft. The use of additional spacers or washers add to the number of parts required to mount the pulley properly and add to the cost of construction.